Mission: The Parent Trap
by Erucchii
Summary: Two girls went to summer camp as strangers, and went back home as sisters and with a mission: get their parents back together. Their aunts and uncles would say they watched too much old movies. And their parents... Their parents would be proud of them, if they didn't kill them first for intervening. 【Disney: The Parent Trap!AU】Warning: Implied mpreg, post-mpreg
1. Prologue

**Mission: The Parent Trap**

 **Prologue**

 **A/N:** I know I shouldn't start a new fanfiction when I have a lot of incomplete works, but I've been working on this one for so long and I really wanted to post it. So...hope everyone enjoys it.

 **Disclaimer:** I do not own The Mortal Instruments.

* * *

Seventeen months has passed since Alec gave birth to the twins, and things had been tense in the Lightwood-Bane household for the last few weeks. Magnus knew that Alec was stressed out, with the babies, and his Masters degree. He helped out as much as he could with the twins and household chores, but sometimes, he still had to walk on eggshells around Alec. His husband was young, heck, both of them were young—still in their early twenties—with Alec two years younger than him. He was Alec's first, official relationship and some might say they tied the knot too quickly.

Times like this made him think that they were right. Alec was still new at this, still so insecure and unsure in their relationship, even though they had been married for almost two years now. It didn't help when he had to work together with Camille Belacourt, and Alec had to find out from the French model that the two of them was in a long-term relationship when they were in form school, or high school to the Americans. Alec had snapped more often then, always suspicious and jealous.

And by the time the collaboration with Camille was over a few weeks later, his family was in shambles. Alec had moved out of their home, temporarily stayed at his cousin's, Gabriel Lightwood, place and took one of the babies with him.

* * *

Alec said nothing when his adopted brother, Jace, came to pick him up at the JFK Airport, and Jace didn't ask him why he decided to return to New York from London without telling anyone, and less one baby and a husband. It started raining heavily as Jace drove them home to Idris, Connecticut, and Alec thought that it was apt, considering his situation. Other than the baby's light snores, the car ride was silent. But that was okay, because Alec knew that when they arrive to their family home, everyone will start bombarding him with questions he didn't even want to think about.

By the time they reached Idris, Alec was surprised when Jace headed to his apartment in town instead of the Lightwood's suburban home. He found out that Jace hadn't told anyone about his return, and said that he probably wouldn't want to face anyone else right now. Which was why Jace took them to his apartment instead. Grateful, he softly thanked his brother.

Surprisingly, it took four days before anyone realized he was back in Idris. It wouldn't be that long if their sister, Isabelle was there too, but she was out on a job in Prague. She was furious for the first few minutes about the situation, before just feeling sad. Never pity though, because she knew he hated that. Fortunately, their parents didn't ask any questions either, or they probably wanted to wait until a more appropriate time to ask.

After moving back into the Lightwood's home, and hours after the baby fell asleep, Alec—although he would deny it later—and Isabelle were cuddling in the lounge, watching some late night TV show while drinking hot chocolate, Isabelle's guilty pleasure. They sat together for hours, shoulder-to-shoulder as his sister comforted him by just being there and not asking more questions than he was willing to answer, and giving him her silent support.

* * *

Magnus was very drunk by the time Clary sent him home. Catarina and Tessa had come to visit him, and he had left his daughter at home with two of his long-time best friends. He wanted to get a drink or two—or more—alone, and had ignored the text messages and phone calls from them and Ragnor, and Will and Jem for the whole night. It was a coincidence that Clary found him, and the redhead, who he treated like a younger sister, just couldn't leave him alone in that state. She sat with him, drank with him, and listened to him as he talked and cried his heart out.

After months, he had finally heard from Alec, and not in a good way. His husband has sent him divorce papers, with all the terms and other legal shit. With those papers, it finally dawned on him that everything was so final now. It finally dawned on him that he would no longer be married to this sweet, and beautiful man with the most beautiful eyes. It finally dawned on him that he would never see his other daughter again. It finally dawned on him that every time he looked at the daughter in his custody, there would be an ache in his heart knowing he wouldn't see the other one grow.

The next morning, Catarina, who stayed over, found him in the twins' room. Only Cecily's now, he thought. He had a hangover, which was the norm for him after drinking the way he did the night before, but he really wanted to see his daughter. He wanted to make sure that Cecily was indeed still there, that his last connection to all he loved hadn't been taken away from him too. By the time Catarina found him, he was crying his heart out next to Cecily's crib, the baby happily babbling away not knowing that she would never know her dad and sister.

* * *

Alec has started avoiding everyone again, and was becoming a recluse. It had been a week since Magnus sent back the divorce papers to him, and he felt the last bit of his heart that hadn't break shattered into pieces. His parents, who were supposed to be in D.C. for a charity gala, reluctantly left. Isabelle and Jace stayed over during that time, not wanting to leave him alone in a big house without anyone there with him. Normally, he would feel affronted about it, but right now, he couldn't bring himself to care.

He was nursing Maxine when a stray thought came to him. He would never nurse Cecily like this ever again. He felt the familiar lump in his throat. He looked down, and saw that Maxine was finally asleep, and she didn't try to resist when he unlatched her from him. Carefully, he lay her down in her crib before returning to his room.

As soon as he was in bed, a sob caught in his throat, escaping in a strangled cry. Then, the tears came, and before long, he was bawling. He vaguely realized Isabelle slipping into the room and joined him on the bed, pulling him into a hug and giving him a shoulder to cry on. He must have fallen asleep, hours later, after exhausting himself emotionally and mentally, but when he woke up, there was food and water for him on his nightstand, and a note telling not to worry about Maxine, that they had things under control. He gripped the note, thankful for his siblings' presence. He didn't know what to do, how he was going to raise Maxine alone, but he was glad that his family was there to help when he needed it.

* * *

 ** _tbc_**

 **A/N:** So, tell me what you think about it. :)


	2. Chapter 1: The Beginning

**Mission: The Parent Trap**

 **Chapter 1:** The Beginning

 **A/N:** Hi there. I know I said I was going to update weekly, but instead, you get the second chapter two months later. I'm sorry. I didn't expect to get so busy during the Ramadhan month, as well as during Eid al-Fitr, and the month after that.  
Anyways, I hope you'll enjoy this chapter.

 **Disclaimer:** I do not own The Mortal Instruments or Disney's The Parent Trap.

* * *

 **20** **th** **June 2026**

Cecily let out a satisfied sigh as she sat on the beach, legs hugged to her chest, watching the ocean waves crashing into each other. It had been three days since she and her papa, Magnus Bane, moved from Brighton to Malibu, and she was already tanned like never before. The weather in Britain couldn't compare to Californian weather.

Two days ago, one of her papa's oldest friend and pseudo sister, Clary, came for a visit. The redhead moved to Los Angeles a few months before them, so she really missed her. When Clary came, the redhead surprised her—and her papa—by bringing with her an acceptance packet to Praetor Lupus Dance and Gymnastics Summer Camp for Girls. She had wanted to apply again this year, but she was told that the camp was full and they were no longer taking any applicants.

So, of course, she was ecstatic. Her papa was not.

She had wanted to go to that particular summer camp for such a long time, mainly because every year, her favourite rhythmic gymnast became a guess instructor there. But her papa always had one excuse or another for her not to go. She didn't know why her papa disliked the summer camp so much. Fortunately, she and Clary managed to change her papa's mind.

She did feel a little bit guilty for leaving her papa to deal with unpacking on his own though.

It seemed like she had let her mind drift because before she realized it, someone had sat beside her and gave her a shoulder nudge. She knew without turning that it was Clary though, from the scent of her floral perfume. She returned the nudge and asked:

"Was my papa really angry at you?"

"Kind of, but he'll forgive me."

Cecily rested her head on Clary's shoulder. "Thank you."

"I didn't really do anything aside from asking Maia to reconsider your application, but you're welcome all the same."

"Still…"

They continued sitting there in silence, observing other people. There are some in the ocean, getting a few more hours of surfing before the sun set, while some others were sun tanning. Kids ran around and build sand castles.

"Clary, do you think I can go and search for my dad while I'm here?" She had sat up straight at this point, and turned to look at the redhead.

Cecily had always been curious about her parentage. As a child, she kept on badgering her papa about it. An opportunity present itself when she had to describe the person who gave birth to her and write a letter to them. Because it was for school, her papa finally sat her down and told her that the person who gave birth to her was a carrier. He told her that his name was Alec, and he was two years younger than him and had the most beautiful blue eyes. But Cecily remembered the sad look on her papa's face when he told her, so she told him she had enough information and ever since that day, she had never asked about her dad anymore.

Clary met her gaze. "Do you want to search for him?"

She bit her bottom lips and looked away. Trying to look for her dad behind her papa's back—because she thought her papa definitely wouldn't let her, and she couldn't ask because she didn't want her papa to look so sad ever again—felt like a betrayal somehow. But she was in the United States now, the same country her dad lived in. She couldn't just continue living without trying to reach out to him. She was about to answer when she caught side of her papa walking out to the deck, a drink in his hand. He saw her looking, and gave her a wave. She returned the wave as she replied; voice almost a whisper, "No."

* * *

 _ **30**_ _ **th**_ _ **September 2020**_

 _Magnus was worried when he picked up Cecily from school and his firecracker wasn't acting like her usual self. Usually, Cecily would be so excited everyday when school ended because that meant it was time for her rhythmic gymnastics lessons. Today, she was reserved._

" _Are you all right, darling?" He looked at her from the corner of his eyes before turning his gaze back to the road._

 _Cecily hugged her bag to her chest. "I'm fine, thank you."_

" _Sweetheart, you know you can tell me anything, right?"_

 _Cecily didn't answer. She was silent for a few minutes before she asked, "Can I skip lessons today? I don't feel like doing gymnastics."_

 _Now Magnus knew something was really wrong because Cecily never skipped lessons unless she was really, really sick and couldn't get out of bed. He stopped at a red light and turned to look at Cecily, but his little girl was curled up looking at the opposite direction. Cecily was so quiet; he would believe she was asleep if it wasn't for the reflection of her blinking on the window._

 _He decided to go straight to the source and called Cecily's schoolteacher._

 _The conversation with Cecily's schoolteacher made him want to drink. Not wanting Cecily to overhear him, he waited for his little girl to go to her room before making the call. His heart ached for his baby when the teacher, Ms. Blythe explained about the task they had to do in class, and how the other children made fun of her when she couldn't turn in her work because she didn't know anything about the person who had given birth to her._

 _After the call ended, Magnus sat in his office, staring blankly at the wall. That was when he decided to tell Cecily anything she wanted to know about Alec, his feelings be damned._

* * *

 **20** **th** **June 2026**

Maxine hugged her friend goodbye, and thanked them for the ride home before taking a deep breath and exhaling. She mentally prepared herself before she entered the house, thinking, 'Time to face the music.' She dropped her dance bag on the couch when she passed the "informal living room"—the smaller of two living rooms in their house—and called out, "Anyone home?"

Instantly, she heard a reply, "In the kitchen." It was her Aunt Isabelle. Maxine shuddered. She hoped Aunt Izzy wasn't trying to cook. The older woman hugged her as soon as she entered the kitchen. She let out a relieved sigh when she saw the entire take out menu on the kitchen table that Aunt Izzy was browsing through before she came in.

"How was your day?" Isabelle asked, returning to her seat.

"It was great, despite what happened with Layla and Mandy." She took a seat in front of Isabelle. "My team is working on a new routine for our group dance. It's a lyrical dance number."

"For the all-camp event?"

Maxine nodded. She took one of the menus on the table and looked through it, before looking at her aunt again. She wondered if her aunt knew. If Isabelle knew, then that meant her dad obviously knew as well. She hadn't seen her dad yet though. "Is daddy down at his office?"

Her dad owned a vineyard, which, lucky for her meant that her dad's office was also on their estate. So, she didn't have to wait too long for her dad to return _if_ he was at the office.

Isabelle shook her head. "Nope. He's out on a date. That's why I'm here and looking at all these menus. I'm supposed to babysit you, and make sure you are fed without giving you food poisoning."

Her eyes widened when she heard the words "on a date", but then pouted when she registered the rest of the sentence. "I don't need to be babysat."

Isabelle shrugged. "I have my orders. Besides, I'm crashing here for the weekend. I don't want to spend the night at the family home, and I don't feel comfortable crashing at Rebecca's apartment when Simon's not here as well."

Simon, Aunt Isabelle's husband, was a recruiter or something for this international company, and he often travelled for work.

"So, a date?" Maxine asked.

"Alec is having dinner with Daniel Rossi. Your dad insisted that it was a business dinner, to finalize their partnership for this business venture or something, but I don't think Daniel intended it to be just a "business" dinner." Isabelle scrunched up her nose in distaste when the name passed her lips.

Maxine frowned. "Daniel Rossi…isn't he the owner of that five star restaurant that dad had been doing business with for the last couple of weeks?"

"He is."

Maxine's frown deepened, but she tried to hide it. She pushed the menu she was looking at—menu from Nando's—and pointed at one item from the list. "I want this one." Then, she said a quick, "Be right back," before leaving the kitchen.

She sprawled on her queen-sized bed, mimicking a starfish, as soon as she arrived into her bedroom. She looked up at the ceiling and sighed, wondering if her dad really was on _just_ a business meeting, or was it a date? She met Daniel Rossi a few times when he came up to the vineyard for a meeting with dad, and she could see that the other man had some interest in her dad. And the thing about her dad was; he could be a bit oblivious until it hit him in the face.

She decided to call him to stop herself from wondering all night long. At least, if she had her dad's word that this wouldn't progress into anything romantic, then she could rest easy. She had nothing against her dad being happy, if he was truly in love. She could make adjustments if the other guy truly loved her dad too, and not just her dad's money, or the recognition the Lightwood name would bring.

Maxine took out her phone and called her dad. The first time, it rang for a long time before going to voicemail. Anxiety started creeping into her as she tried again. Fortunately, this time her dad answered at the second ring.

"Daddy," she said, breathing a sigh of relief when she heard his voice.

" _I'm sorry I didn't answer earlier. I had my phone on silent_." After a short pause, he continued, " _Are you okay? I left you a note_."

Leaving notes was something they did, if one of them were going out before the other gets home.

"I haven't seen it, but I saw Aunt Izzy."

" _Let me guess, she called this a dinner date_."

"Is it?"

Alec's sigh could be heard from the other line. " _Maxie, I've promised you, didn't I? I would never start anything without talking to you first."_ Not again, was left unsaid.

"I know, I'm sorry. I was just being silly."

" _It's fine. I have to go now, sweetie, but I'll be home before midnight, okay? Then, tomorrow we could talk. I received a rather interesting phone call from Sandra Anderson earlier today about you attacking her daughter."_

Maxine squawked. There it was, the thing she was dreading. "It wasn't my fault," she exclaimed.

Alec chuckled. " _We'll talk about it tomorrow._ " There was a short pause again, before he continued, " _Listen, I really need to go now, okay? Order some take out, don't eat anything Izzy cooked, and make sure to pack your stuff. Camp's in two days after all."_

Maxine giggled. Aunt Izzy's cooking was legendary for being inedible. Hers and her dad's cooking weren't great either, but it was at least edible. People called it "the Lightwood curse". Uncle Jace was the only one who could cook in their family, but then, that was because he was adopted into the Lightwood family. She told her dad to have fun, but not too much, before ending the call.

Satisfied, she had a smile on her face as she got up and went to take a shower.

* * *

 _ **4th April 2019**_

 _A silent Jace was waiting for him when he arrived home that day. All his siblings and his parents had a spare key to his house so he wasn't worried when he saw Jace there. However, he was curious about why Jace looked so furious. Jace didn't outright say it but he knew because the blond didn't greet him in a loud or boisterous way, or didn't give him a hug or a clap on the back. His brother just looked at him with a frown on his face and arms crossed over his chest._

" _Did something happened?" he asked._

" _Where were you?"_

" _I went out for lunch with Sebastian. Why?" Alec frowned._

 _Jace sighed, dropping his posture and ran a hand through his hair. "Maxine's teacher tried to call you. She's sick. They called me when the call went to voicemail after five times."_

 _A feeling of dread crept into Alec as he fished out his phone and unlocked it. There was no notification for him, but when opened his call logs, indeed there were five missed calls from Maxine's elementary school, Alicante Academy. "I…I left my phone on the table with Sebastian when I went to the toilet."_

" _When are you going to break up with him?"_

" _I…"_

" _Alec, come on. What more do you need? Izzy and I told you that Sebastian didn't like Maxine and here's one proof. Do you want to wait for him to send your daughter off to boarding school before you do something?"_

" _No," Alec said, and Jace could hear the anger in his voice._

' _Good,' the blond thought._

 _Alec excused himself and immediately went to Maxine's room. His baby was asleep, tucked in her bed, with a wet towel on her forehead. He sat on the edge of her bed, and brushed away a few strands of hair that fell onto her face._

" _I'm so sorry," he whispered to the sleeping Maxine, careful not to wake the younger girl up. "I did something that I swore to myself I would never do." He placed a kiss softly on Maxine's forehead. "I promise I'll break up with Sebastian immediately, and we would never have him in our lives ever again."_

 _After spending a few more minutes watching his baby girl sleep, he went down to the kitchen to start making dinner while making a mental note to talk to Maxine about this once she was awake and feeling better. To his surprise—really, he shouldn't be anymore because Jace had always done this, all the time—there was already a pot of chicken soup, and rice porridge cooking on the stoves. Jace himself was still in the kitchen, standing by the kitchen island, working on who-knows-what._

* * *

 **22** **nd** **June 2026**

Cecily was glad that growing up, her papa and his friends were a constant in her life. Because it had prepared her for surprise hugs. Case in point, as soon as she entered the Camp Director's office to complete her registration, Maia Roberts, the Camp Director, stood up and hugged her tightly. She heard from Clary that Maia was one of her papa's friends, back when he still lived in Brooklyn. Only, Clary didn't say "papa" or her papa's name. She used the word "parents".

Clary thought she was subtle, but Cecily could see where the older woman was going with that hint. Or so she thought.

"…under no circumstances are you—Am I making you bored?" Maia asked when she noticed that Cecily was no longer paying attention.

Cecily snapped her attention back to the dark-skinned woman. She flushed under the woman's gaze. "I'm sorry. This was just fascinating," she replied, gesturing at the general attention of Maia's walls.

There were picture frames hung on the wall, and on the shelves near the wall. But what made her notice the pictures was her papa. He was in some of those pictures, and also the man she could identify as her dad. Suddenly, it clicked inside her brain that perhaps all of these—the special favour into the camp, the hints, and the painted portrait of her parents that Clary slipped into her luggage—it was all some kind of plan to make Cecily want to search for her dad.

Cecily didn't know why Clary was doing all this yet, but it won't make her change her mind.

Maia nodded understandingly. "See anything you like?"

Cecily nodded. "They all looked so young… You _all_ looked so young." Then, realizing what she had said, she blushed. "I mean…not that you don't look young now but…"

Maia laughed. "I get what you meant." Then, she straightened up and went all business mode again. "So, I've explained the important rules to you, and all the other fussy ones, you can just read from the pamphlet provided in your acceptance package." After Cecily nodded, Maia continued, "Great. Now, you've already signed up for the dance and gymnastic classes before you got here, but if you changed your mind about any of the classes, or felt like adding some more—if it doesn't clash with your other classes—then, all you need to do is talk to your cabin counsellor and she will deal with the rest."

"Okay."

"The same goes for your "free time" activities. Please inform your cabin counsellor before going on the more adventurous activities like hiking or swimming in the lake. We don't want any accidents. Do I make myself clear?"

"Crystal," Cecily nodded.

"One last thing," Maia added. "You might not be aware, but most of the campers here have known each other for quite some time, so some has probably already have a set team for the all-camp event. However, don't let discourage you to find and join any of the teams, okay? We encourage all campers to participate in the all-camp event."

"Got it," Cecily said, trying to find cheery but she somehow dreaded it. She doesn't work well in teams, which was why she only competed in the individual event, and never the group event in Rhythmic Gymnastics.

After they chatted for a few more minutes, and Cecily signed everything she needed to sign, Maia walked her out of the administration building. As she was walking down the stairs of the porch, her shoulder brushed with another camper who was going the opposite direction. She immediately apologized. The other camper didn't stop walking but the camper did managed to reply with a "No worries" before the camper cried out the Camp Director's name, and Cecily heard Maia replied with a "Maxine" and there was an amused hint in Maia's voice. She turned around just in time to see Maxine and Maia hug. She just shrugged before going off to find her cabin, and meet her cabin counsellor and cabin mates.

* * *

 **A/N:** Because I mainly use AO3 nowadays, I posted this new chapter on A03 first. And well, comments about Alec was kind of overwhelming. Anyways, please comment. I would love to hear your thoughts.


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